As long as the post fits through the hole in the headstock, you can deal with any other issues that might come up, like set screw placement. When I put Hipshot ultralights on my '91 Gibson, I had to drill the openings to make them fit. After that, drilling holes in anything at all didn't bother me. I have put different bass x-tenders on several Gibsons since then (not the '91 yet, oddly enough), and they have dropped right in. One isn't an exact match for the other tuners because I bought the wrong one, but it fit without a problem. Get close on post size, and then match or don't match what the machines themselves look like and you will be able to modify the headstock as necessary to make them fit.
And now the disclaimer - I approach everything from the standpoint of a CroMagnon with a stone axe and not a whole lot of finesse. Worst case, measure the post and call Hipshot. If they can't figure it out, nobody can.